// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
#define MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_

#include <AudioUnit/AudioUnit.h>
#include <CoreAudio/AudioHardware.h>
#include <stddef.h>

#include <list>
#include <map>
#include <memory>
#include <string>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "media/audio/audio_manager_base.h"
#include "media/audio/mac/audio_device_listener_mac.h"

namespace media {

class AUAudioInputStream;
class AUHALStream;

// Mac OS X implementation of the AudioManager singleton. This class is internal
// to the audio output and only internal users can call methods not exposed by
// the AudioManager class.
class MEDIA_EXPORT AudioManagerMac : public AudioManagerBase {
public:
    AudioManagerMac(
        scoped_refptr<base::SingleThreadTaskRunner> task_runner,
        scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
        AudioLogFactory* audio_log_factory);

    // Implementation of AudioManager.
    bool HasAudioOutputDevices() override;
    bool HasAudioInputDevices() override;
    void GetAudioInputDeviceNames(AudioDeviceNames* device_names) override;
    void GetAudioOutputDeviceNames(AudioDeviceNames* device_names) override;
    AudioParameters GetInputStreamParameters(
        const std::string& device_id) override;
    std::string GetAssociatedOutputDeviceID(
        const std::string& input_device_id) override;
    const char* GetName() override;

    // Implementation of AudioManagerBase.
    AudioOutputStream* MakeLinearOutputStream(
        const AudioParameters& params,
        const LogCallback& log_callback) override;
    AudioOutputStream* MakeLowLatencyOutputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback) override;
    AudioInputStream* MakeLinearInputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback) override;
    AudioInputStream* MakeLowLatencyInputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback) override;
    std::string GetDefaultOutputDeviceID() override;

    // Used to track destruction of input and output streams.
    void ReleaseOutputStream(AudioOutputStream* stream) override;
    void ReleaseInputStream(AudioInputStream* stream) override;

    // Called by AUHALStream::Close() before releasing the stream.
    // This method is a special contract between the real stream and the audio
    // manager and it ensures that we only try to increase the IO buffer size
    // for real streams and not for fake or mocked streams.
    void ReleaseOutputStreamUsingRealDevice(AudioOutputStream* stream,
        AudioDeviceID device_id);

    static bool GetDeviceChannels(AudioDeviceID device,
        AudioObjectPropertyScope scope,
        int* channels);

    static int HardwareSampleRateForDevice(AudioDeviceID device_id);
    static int HardwareSampleRate();

    // OSX has issues with starting streams as the system goes into suspend and
    // immediately after it wakes up from resume.  See http://crbug.com/160920.
    // As a workaround we delay Start() when it occurs after suspend and for a
    // small amount of time after resume.
    //
    // Streams should consult ShouldDeferStreamStart() and if true check the value
    // again after |kStartDelayInSecsForPowerEvents| has elapsed. If false, the
    // stream may be started immediately.
    // TOOD(henrika): track UMA statistics related to defer start to come up with
    // a suitable delay value.
    enum { kStartDelayInSecsForPowerEvents = 5 };
    bool ShouldDeferStreamStart() const;

    // True if the device is on battery power.
    bool IsOnBatteryPower() const;

    // Number of times the device has resumed from power suspension.
    size_t GetNumberOfResumeNotifications() const;

    // True if the device is suspending.
    bool IsSuspending() const;

    // Changes the I/O buffer size for |device_id| if |desired_buffer_size| is
    // lower than the current device buffer size. The buffer size can also be
    // modified under other conditions. See comments in the corresponding cc-file
    // for more details.
    // |size_was_changed| is set to true if the device's buffer size was changed
    // and |io_buffer_frame_size| contains the new buffer size.
    // Returns false if an error occurred.
    bool MaybeChangeBufferSize(AudioDeviceID device_id,
        AudioUnit audio_unit,
        AudioUnitElement element,
        size_t desired_buffer_size,
        bool* size_was_changed,
        size_t* io_buffer_frame_size);

    // Number of constructed output and input streams.
    size_t output_streams() const { return output_streams_.size(); }
    size_t low_latency_input_streams() const
    {
        return low_latency_input_streams_.size();
    }
    size_t basic_input_streams() const { return basic_input_streams_.size(); }

protected:
    friend class media::AudioManagerDeleter;

    ~AudioManagerMac() override;
    AudioParameters GetPreferredOutputStreamParameters(
        const std::string& output_device_id,
        const AudioParameters& input_params) override;

private:
    void InitializeOnAudioThread();

    int ChooseBufferSize(bool is_input, int sample_rate);

    // Notify streams of a device change if the default output device or its
    // sample rate has changed, otherwise does nothing.
    void HandleDeviceChanges();

    // Returns true if any active input stream is using the specified |device_id|.
    bool AudioDeviceIsUsedForInput(AudioDeviceID device_id);

    // This method is called when an output stream has been released and it takes
    // the given |device_id| and scans all active output streams that are
    // using this id. The goal is to find a new (larger) I/O buffer size which
    // can be applied to all active output streams since doing so will save
    // system resources.
    // Note that, it is only called if no input stream is also using the device.
    // Example: two active output streams where #1 wants 1024 as buffer size but
    // is using 256 since stream #2 wants it. Now, if stream #2 is closed down,
    // the native I/O buffer size will be increased to 1024 instead of 256.
    // Returns true if it was possible to increase the I/O buffer size and
    // false otherwise.
    // TODO(henrika): possibly extend the scheme to also take input streams into
    // account.
    bool IncreaseIOBufferSizeIfPossible(AudioDeviceID device_id);

    std::unique_ptr<AudioDeviceListenerMac> output_device_listener_;

    // Track the output sample-rate and the default output device
    // so we can intelligently handle device notifications only when necessary.
    int current_sample_rate_;
    AudioDeviceID current_output_device_;

    // Helper class which monitors power events to determine if output streams
    // should defer Start() calls.  Required to workaround an OSX bug.  See
    // http://crbug.com/160920 for more details.
    class AudioPowerObserver;
    std::unique_ptr<AudioPowerObserver> power_observer_;

    // Tracks all constructed input and output streams.
    // TODO(alokp): We used to track these streams to close before destruction.
    // We no longer close the streams, so we may be able to get rid of these
    // member variables. They are currently used by MaybeChangeBufferSize().
    // Investigate if we can remove these.
    std::list<AudioInputStream*> basic_input_streams_;
    std::list<AUAudioInputStream*> low_latency_input_streams_;
    std::list<AUHALStream*> output_streams_;

    // Maps device IDs and their corresponding actual (I/O) buffer sizes for
    // all output streams using the specific device.
    std::map<AudioDeviceID, size_t> output_io_buffer_size_map_;

    // Set to true in the destructor. Ensures that methods that touches native
    // Core Audio APIs are not executed during shutdown.
    bool in_shutdown_;

    DISALLOW_COPY_AND_ASSIGN(AudioManagerMac);
};

} // namespace media

#endif // MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
